Zoonotic pathogens derived from an animal reservoir account for some 60-75% of emerging infectious diseases in humans, a disproportionate number of which take place in resource poor countries where the economic and social burden of corresponding health crises is greatest. Bats have received much attention in recent years for their role as the putative reservoir hosts for a number of high profile, virulent zoonoses, including Ebola and Marbug filoviruses, Hendra and Nipah henipaviruses, and SARS coronavirus, all of which demonstrate peaks in transmission?both between bats and from bats to spillover hosts (including humans)?during the resource-poor dry season for the system in question. Seasonal forcings are known to play an important role in driving epidemic cycles in infectious diseases for both humans and wildlife, though the mechanistic drivers of seasonality can sometimes be difficult to identify. In bat systems, researchers have posited that dynamical patterns could result from pulsed additions of annual, synchronous births to the pool susceptible to immunizing viruses, while others have suggested that bats might instead maintain these viruses as persistent infections across the duration of their lifespans and undergo periodic bouts of viral shedding. A true understanding of these dynamics will be essential to predicting and preventing the next bat zoonosis, a critical public health aim for developing world countries, like Madagascar, where we base our work. To date, longitudinal data of a fine enough scale do not exist to distinguish among the proposed hypotheses. Our project brings together a diverse team of molecular biologists from Institut Pasteur de Madagascar and Duke-NUS, epidemiological modelers from Princeton, and field ecologists from Harvard to address these challenges. In Aim 1 of our research, we introduce novel Luminex assays to identify henipa/filo/corona/lyssavirus antibodies in both bat and human serum samples in Madagascar. In Aim 2, we build mechanistic transmission models exploring the proposed hypotheses of seasonal drivers of infection dynamics in bat systems, and in Aim 3, we unite these goals in a longitudinal model- guided field study, with corresponding serological and molecular analyses, which will generate the data needed to enable effective model comparison and evaluation. Our work addresses questions of critical interest to both evolutionary biology and public health, while simultaneously building scientific capacities in the developing world.